This invention is directed to an externally applied coupling and sealing system that provides thrust restraint to a pair of aligned tubular members. Preferably, the system hereof utilizes an inflatable, elastomeric sealing gasket which encircles and applies pressure to the walls of the tubular members forming the joint therebetween. An alternate embodiment uses an inflated or pressurized thin metal chamber for low pressure transmission systems for exhaust or other special high temperature applications.
There have been prior art attempts to incorporate inflatable sealing members into a system that offers a temporary means to effect sealing of a tubular member. The U.S. Pat. Nos. 4,786,087, to Thewlis et al., and 4,741,561, Morita et al., represent two such attempts.
Thewlis et al. teach a quick disconnect coupling system for transmitting chemicals, for example, from a storage tank to a reactor tank or vessel. Briefly, one end of the coupling system is connected to a storage tank containing the chemicals. The other end of the coupling system is a rigid pipe connected to one end of a hose for transferring the chemicals of the storage tank to a reactor tank. The outlet pipe has a concentrically mounted rigid tube secured thereto via an annular flange which cooperates to receive the rigid pipe. An inflatable tube or mandrel is located between the rigid pipe and the rigid tube which is connected to the outlet pipe such that on inflation of the inflatable tube the rigid pipe is securely fastened to the outlet pipe and its concentrically mounted rigid tube to provide a sealing connection for transfer of materials from the storage tank to the reactor tank. Such a coupling system is necessarily limited to temporary and low pressure transmissions. It cannot be adapted to high pressure transmissions as it does not afford significant thrust restraint. For such system, thrust restraint is solely dependent on friction between the outer pipe surface or wall and the inflatable tube.
Morita et al. teach a seal for a connection joint that has particular utility for piping in a nuclear power plant. Specifically, the joint is a bell spigot joint composed of a male pipe and a female pipe end. The male and female pipe ends are removably engaged with gaskets. The gaskets are inflatable and arranged in a plurality of stages in the axial direction to inflatable seal a clearance between the pipe ends, and the joint has a clamp device for clamping the two pipe ends so that the pipe ends can be engaged and disengaged. The gaskets are positioned in machined annular grooves integral with the inner wall of the female pipe end.
U.S. Pat. No. 4,448,218 to Vetter teaches an apparatus for sealing leaks in conduits, such as pipes. The apparatus thereof includes a rectangularly inflatable pad comprising top and bottom layers with top layer constructed of inelastic material and the bottom layer of very elastic material connected together. The pad has mutually opposite side strips and mutually opposing frontal and rear strips. Straps are provided for attachment to the side strips for securing the pad about a leak in a pipe, or the like. The pad is provided with a valve and member for inflating the pad.
The present invention avoids many of the shortcomings of the prior art by providing a reusable, on-site applied system for sealing leaks and joints in a high pressure, or other special application in a transmission line. The unique features hereof will become apparent in the specification which follows.